Duv is a signed measure of how far a light’s chromaticity lies from the Planckian, or blackbody, locus in the CIE 1960 u,v diagram. Positive values lie above the locus; negative values lie below it. Near white, this is commonly associated with a greener or more magenta appearance respectively.
Reading Duv alongside CCT
CCT locates the approximate warm-to-cool balance. Duv adds information about the departure from the blackbody reference. Two lights can both read 5600 K while giving noticeably different tint on a neutral surface. Neither number describes the complete spectrum or predicts every camera’s response.
Practical example
Measure two fixtures individually at the subject position, using the same meter setup. If their CCT readings agree but their Duv readings differ, adjust tint or test correction filters before deciding that the fixtures match. Check the result on the production camera and a neutral reference.
Meter readings and fixture controls
A fixture’s green/magenta slider may use a manufacturer-specific scale. A setting of +0.10 on the fixture does not automatically mean Duv +0.010. Record the measured value separately from the menu setting, along with CCT, dimming level and modifier.
Equipment examples
The Nanlite Forza 300B II offers green/magenta adjustment. Use a measured tint reading and a camera test to judge a match; its control value is a fixture setting.
Related terms
CCT (Correlated Colour Temperature) · Plusgreen · Minusgreen · SSI (Spectral Similarity Index)